1. Field of the Invention
The present invention relates to a novel iron core coil motor and a disk drive and more specifically to a technique to control generation of noise and vibration.
2. Description of the Related Art
In a certain iron core coil motor, removing of rotor in the axial direction is prevented by utilizing an attracting force which is generated by deviating the centers of magnetism of the iron core of coil and rotor magnet.
In the iron core coil motor of the related art explained above, if attracting force is too weak, a rotor seems to be floated, resulting in a problem that vibration (hopping noise) is easily generated. When such a motor is used as a spindle motor of the disk drive, read error of signal may be generated due to vibration and particularly when resonance is generated, there rises a problem that read operation becomes almost impossible.
On the contrary, if attracting force is too intensive, noise (switching noise) is generated due to a vibration accelerating force in the axial direction which is generated at the time of switching because of a difference of magnetic flux density in the axial direction of iron core, thereby resulting in a problem that operating conditions are not so good.
It is therefore an object of the invention to control generation of noise and vibration generated during operation.
An iron core coil motor of the present invention successfully realizes, in order to solve the problems explained above, that an attracting force generated when the centers of magnetism of iron core of coil and rotor magnet are deviated is set to 0.8 to 2.0 times the weight of all rotating members including the rotor.
Therefore, in the iron core coil motor of the present invention, hopping noise is not generated even if the coil motor is used in the vertical attitude and moreover switching noise is never generated.
In addition, the disk drive of the present invention realizes, in a spindle motor utilizing the iron core coil motor, that an attracting force generated when the centers of magnetism of iron core of coil and rotor magnet are deviated is set to 0.8 to 2.0 times the total weight of the rotating members including a turn table and a disk type storage medium or the like.
Therefore, in the disk drive of the present invention, hopping noise is not generated and signal read error is not easily generated even when the motor is used in the vertical attitude (the rotating axis becomes horizontal). Moreover, switching noise is not generated and thereby good operating condition can be maintained.